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diff --git a/Documentation/userspace-api/media/dvb/frontend-stat-properties.rst b/Documentation/userspace-api/media/dvb/frontend-stat-properties.rst new file mode 100644 index 000000000..223c1c56c --- /dev/null +++ b/Documentation/userspace-api/media/dvb/frontend-stat-properties.rst @@ -0,0 +1,245 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later + +.. _frontend-stat-properties: + +****************************** +Frontend statistics indicators +****************************** + +The values are returned via ``dtv_property.stat``. If the property is +supported, ``dtv_property.stat.len`` is bigger than zero. + +For most delivery systems, ``dtv_property.stat.len`` will be 1 if the +stats is supported, and the properties will return a single value for +each parameter. + +It should be noted, however, that new OFDM delivery systems like ISDB +can use different modulation types for each group of carriers. On such +standards, up to 3 groups of statistics can be provided, and +``dtv_property.stat.len`` is updated to reflect the "global" metrics, +plus one metric per each carrier group (called "layer" on ISDB). + +So, in order to be consistent with other delivery systems, the first +value at :c:type:`dtv_property.stat.dtv_stats <dtv_stats>` array refers +to the global metric. The other elements of the array represent each +layer, starting from layer A(index 1), layer B (index 2) and so on. + +The number of filled elements are stored at ``dtv_property.stat.len``. + +Each element of the ``dtv_property.stat.dtv_stats`` array consists on +two elements: + +- ``svalue`` or ``uvalue``, where ``svalue`` is for signed values of + the measure (dB measures) and ``uvalue`` is for unsigned values + (counters, relative scale) + +- ``scale`` - Scale for the value. It can be: + + - ``FE_SCALE_NOT_AVAILABLE`` - The parameter is supported by the + frontend, but it was not possible to collect it (could be a + transitory or permanent condition) + + - ``FE_SCALE_DECIBEL`` - parameter is a signed value, measured in + 1/1000 dB + + - ``FE_SCALE_RELATIVE`` - parameter is a unsigned value, where 0 + means 0% and 65535 means 100%. + + - ``FE_SCALE_COUNTER`` - parameter is a unsigned value that counts + the occurrence of an event, like bit error, block error, or lapsed + time. + + +.. _DTV-STAT-SIGNAL-STRENGTH: + +DTV_STAT_SIGNAL_STRENGTH +======================== + +Indicates the signal strength level at the analog part of the tuner or +of the demod. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_DECIBEL`` - signal strength is in 0.001 dBm units, power + measured in miliwatts. This value is generally negative. + +- ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% + measurement for power (actually, 0 to 65535). + + +.. _DTV-STAT-CNR: + +DTV_STAT_CNR +============ + +Indicates the Signal to Noise ratio for the main carrier. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_DECIBEL`` - Signal/Noise ratio is in 0.001 dB units. + +- ``FE_SCALE_RELATIVE`` - The frontend provides a 0% to 100% + measurement for Signal/Noise (actually, 0 to 65535). + + +.. _DTV-STAT-PRE-ERROR-BIT-COUNT: + +DTV_STAT_PRE_ERROR_BIT_COUNT +============================ + +Measures the number of bit errors before the forward error correction +(FEC) on the inner coding block (before Viterbi, LDPC or other inner +code). + +This measure is taken during the same interval as +``DTV_STAT_PRE_TOTAL_BIT_COUNT``. + +In order to get the BER (Bit Error Rate) measurement, it should be +divided by +:ref:`DTV_STAT_PRE_TOTAL_BIT_COUNT <DTV-STAT-PRE-TOTAL-BIT-COUNT>`. + +This measurement is monotonically increased, as the frontend gets more +bit count measurements. The frontend may reset it when a +channel/transponder is tuned. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of error bits counted before the inner + coding. + + +.. _DTV-STAT-PRE-TOTAL-BIT-COUNT: + +DTV_STAT_PRE_TOTAL_BIT_COUNT +============================ + +Measures the amount of bits received before the inner code block, during +the same period as +:ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>` +measurement was taken. + +It should be noted that this measurement can be smaller than the total +amount of bits on the transport stream, as the frontend may need to +manually restart the measurement, losing some data between each +measurement interval. + +This measurement is monotonically increased, as the frontend gets more +bit count measurements. The frontend may reset it when a +channel/transponder is tuned. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring + :ref:`DTV_STAT_PRE_ERROR_BIT_COUNT <DTV-STAT-PRE-ERROR-BIT-COUNT>`. + + +.. _DTV-STAT-POST-ERROR-BIT-COUNT: + +DTV_STAT_POST_ERROR_BIT_COUNT +============================= + +Measures the number of bit errors after the forward error correction +(FEC) done by inner code block (after Viterbi, LDPC or other inner +code). + +This measure is taken during the same interval as +``DTV_STAT_POST_TOTAL_BIT_COUNT``. + +In order to get the BER (Bit Error Rate) measurement, it should be +divided by +:ref:`DTV_STAT_POST_TOTAL_BIT_COUNT <DTV-STAT-POST-TOTAL-BIT-COUNT>`. + +This measurement is monotonically increased, as the frontend gets more +bit count measurements. The frontend may reset it when a +channel/transponder is tuned. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of error bits counted after the inner + coding. + + +.. _DTV-STAT-POST-TOTAL-BIT-COUNT: + +DTV_STAT_POST_TOTAL_BIT_COUNT +============================= + +Measures the amount of bits received after the inner coding, during the +same period as +:ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>` +measurement was taken. + +It should be noted that this measurement can be smaller than the total +amount of bits on the transport stream, as the frontend may need to +manually restart the measurement, losing some data between each +measurement interval. + +This measurement is monotonically increased, as the frontend gets more +bit count measurements. The frontend may reset it when a +channel/transponder is tuned. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of bits counted while measuring + :ref:`DTV_STAT_POST_ERROR_BIT_COUNT <DTV-STAT-POST-ERROR-BIT-COUNT>`. + + +.. _DTV-STAT-ERROR-BLOCK-COUNT: + +DTV_STAT_ERROR_BLOCK_COUNT +========================== + +Measures the number of block errors after the outer forward error +correction coding (after Reed-Solomon or other outer code). + +This measurement is monotonically increased, as the frontend gets more +bit count measurements. The frontend may reset it when a +channel/transponder is tuned. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of error blocks counted after the outer + coding. + + +.. _DTV-STAT-TOTAL-BLOCK-COUNT: + +DTV-STAT_TOTAL_BLOCK_COUNT +========================== + +Measures the total number of blocks received during the same period as +:ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` +measurement was taken. + +It can be used to calculate the PER indicator, by dividing +:ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>` by +:ref:`DTV-STAT-TOTAL-BLOCK-COUNT`. + +Possible scales for this metric are: + +- ``FE_SCALE_NOT_AVAILABLE`` - it failed to measure it, or the + measurement was not complete yet. + +- ``FE_SCALE_COUNTER`` - Number of blocks counted while measuring + :ref:`DTV_STAT_ERROR_BLOCK_COUNT <DTV-STAT-ERROR-BLOCK-COUNT>`. |